This invention relates to a plate type press filter, particularly of the type which has horizontally superimposed, movable filter plates between which there is disposed an endless, movable filter cloth which is deflected by deflecting rolls and which passes through a driving station. The press filter further includes a preferably hydraulic closing device which affects the filter plates and which is connected to a closing pressure regulator.
Plate type press filters having vertically oriented filter plates are disclosed, for example, in German Pat. No. 1,138,739, while plate type press filters having horizontally oriented filter plates are disclosed, for example, in German Pat. No. 1,461,500. Up till now, in such filters it was sufficient to maintain the plate stack in a closed position with a predetermined pressure which has been of such a magnitude that it takes up the inner press pressure during the filtering process and effects a sufficient seal between the individual filter plates. With increasing structural dimensions and in large-output filters utilizing high pressure, particularly, however, in plate type press filters of the above-outlined type, the sealing faces are, in such a mode of operation, exposed to such a stress that they are destroyed after a short operational period if the closing pressure for moving to one another the filter plates of the stack is designed to equal the inner filter pressure, although such an inner pressure is not yet present. In plate type press filters of the above-outlined type there are further experienced difficulties in the advance of the filter cloth in case more than 20 filter plates are present, because with the growing number of deflecting rollers and the contacting surfaces between the filter cloth and the filter plates, the frictional forces to be overcome attain such a high value that the filter cloth will be overloaded in the zone of the drive station.